1012 A TREATISE ON METAMORPHISM . 



crevices would be closed. The rate of closing - would depend upon many 

 factors. (See pp. 766-768.) 



Since this conclusion was reached, Adams and Nicolson" have 

 actually deformed marble under .the conditions supposed to exist at 

 moderate depth, with the result that the rock changed its form with no 

 perceptible openings. 



Before the above inductive reasoning or Adams and Nicolson's 

 experiments were made, I had become convinced from observation that 

 at moderate depth rocks are deformed with fracture and differential 

 movements between the solid particles (granulation), and by continuous 

 solution and redeposition by underground water (recrystallization). 



It has been explained (pp. 189-190) that the maximum possible 

 depth of the zone of fracture for the strongest rocks under quiescent 

 conditions is not greater than 10,000. or 12,000 meters, and that for the 

 majority of rocks, and especially under conditions of movement, the zone 

 of flowage is probably reached at depths much less than this. 



OPENINGS OF ZONE OF FLOWAGE. 



The openings of the zone of flowage are dominantly subcapillary. 

 Capillary opening's are numerous, but they are not usually continuous for 

 any considerable distance. Supercapillary openings may exceptionally* 

 exist in the upper part of the zone of flowage in consequence of very rapid 

 deformation, but such openings are likely to be temporary, for when rapid 

 deformation ceases they are closed by flowage. 



REACTIONS OF ZONE OF FLOWAGE. 



The chemical reactions of the zone of anamorphism, as fully explained 

 in Chapters IV and VIII, are dominantly those of silication, dehydration, 

 deoxidation so taking place as to decrease volume. 



RELATIONS BETWEEN ZONES OF DEFORMATION. 



From the preceding pages it is clear that the zones of fracture, of com- 

 bined fracture and flowage, and of flowage are not sharply separated from 

 one another. 



"Adams, F. D., and Nicolson, J. T., An experimental investigation into the flow of marble: 

 Phil. Trans. R05'. Soc. London, ser. a, vol. 195, 1901, pp. 363-401. 



